Plan i meter



(No Model.)

-B. E.OHOLLA R PLANIMETER.

Patented Jan. 12, 1897.

as co. woroumo. WASHXNGTON. u c.

I reference being had to the accompanying which-- ter; 2, theperpendicular portion, terminattively, the positions shown at 10, 11,and 12.

v UNITED STATES ATEN'I FFICE.

BYRON E. CHOLLAR, OF ST. LOUIS, MISSOURI.

PLANIMETER.

SPECIFICATION forming part of Letters Patent No. 575,105, dated January12, 1897. I Application filed July 16, 1896. Serial No. 599,371; (Nomodel.)

To all whont it may concern:

Be it known that I, BYRON E. CHOLLAR, a citizen of the United States,residing at the city of St. Louis, in the State of Missouri, haveinvented a certain new and useful Improvement in Planimeters, of whichthe following is a full, clear, and exact description,

drawings, forming part of this specification. My invention relates to animprovement in instruments for ascertaining the area of irregular planesurfaces. I am aware that the instrument itself is old, but my inventionrelates to an improved attachment therefor.

The device is shown in the drawings, in

Figure I illustrates a perspective view thereof. Fig. II illustrates adiagram showing the various positions of the parts during themeasurement of a surface.

1 is the horizontal portionof the planimeing in a point, said pointbeing adapted to trace the boundaries of the surface to be measured.

3 is the second perpendicular portion of the instrument, being in thesame plane as the other portions and terminating in a flat knifeedge,the said edge being in the plane of the portions 1, 2, and 3.

4 is a sleeve adapted to fit over and support the upright 2.

5 is a ring attached to the sleeve 4 by means of the braces 6.

7 is a knife-edge in line with point 2 and provided with a cut at itspoint of contact and situated on the end of upright 3.

For the purpose of illustrating the use of my invention we will assumethat the circle 8 incloses the area to be ascertained. By placing thepointed end of 2 in the center of this circle the edge. 7 will fall uponthe place 7 as shown in Fig. II. The point of 2 is then moved down theradius r to the circumference. The supporting-ring 5 will then be in theposition shown at 9, while the center of edge 7, which has been allowedto swing freely, will be at 9. The point 2 being traced over thecircumference, as shown by the arrow, causes the ring 5 to take,consecu- The edge 7 beingin the meantime allowed to I travel freely willbe in the positions 1O 11 12. When the point has returned to the end ofthe radius r, the edge 7 will be at 13. Then the point 2 is traced backup the radius r to the center, at which place it will be found that theedge 7 rests at 14. The distance from 14 to 7, the place of starting,multiplied by the distance from point 2 to the point of contact of edge7 will give the area thereof. Formerly the bent wire 1 2 3 was all thatwas used. As great care and exactness are required, the necessaryfreedom of the loose end 7 was impaired by the handling of the device.The pointed end 2 must exactly trace the boundary of the surface, whilethe end 7 must be allowed to move freely. Holding the instrument in thehand prevented this. I have therefore provided the collar 4, throughwhich the pointed end 2 plays, supported by braces from a fiat ring 5.The ring 5 is large enough to expose the pointed end 2 to ones view. Thecollar 4 holds the instrument upright, and the braces 6 afford aconvenient means for holding or moving the device. By its use accurateresults may be obtained with an case that has not before been possible.

What I claim, and desire to secure by Letters Patent, is-

l. The combination with a planimeter, of a frame adapted to seat on thesurface to be traced whereby the pointed upright of the planimeter issupported in contact with the said surface; substantially as described.

2. The combination of a pointed upright, a knife-edge upright, and aconnection between the two, a collar adapted to support said pointedupright, and a horizontal ring secured to said collar by means ofbraces, substantially as described.

3. The combination of tracing-upright 2, knife-edge upright 3, andconnection 1, all made integral, with supporting-collar 4 adapted toreceivesaid tracing-upright 2, horizontal ring 5, and braces 6, likewisemade integral, substantially as described.

BYRON E. CHOLLAR.

